There are several main diving organizations offering courses from the beginners’ level to the professional. The The teaching techniques and materials content differ slightly. But, of course, PADI use different books and decompression tables than BSAC. Although PADI and BSAC courses teach pretty much the same and their levels are more or less equivalents, the cross-over from one course to another may be confusing due to the discrepancies in materials, different terms, etc. Usually, the main differences in courses are the length of the course and the price. However, every course is to help people enjoy and improve their diving.